Composition for providing an abrasion resistant coating on a substrate with a matched refractive index:2

ABSTRACT

The present invention discloses compositions as well as methods of making and using said compositions, having improved stability which, when applied to a variety of substrates and cured, form transparent coatings having abrasion resistant properties and a matched refractive index to that of the substrate. The compositions comprise an aqueous-organic solvent mixture containing a mixture of hydrolysis products and partial condensates of an epoxy-functional silane, a carboxylic acid functional compound selected from the group consisting of carboxylic acids, multifunctional carboxylic acids, anhydrides, and combinations thereof, a metal oxide composite colloid, a colloidal silica material, and a tetrafunctional silane. The coating compositions of the present invention may further include a mixture of hydrolysis products and partial condensates of one or more silane additives.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) of U.S.Provisional Ser. No. 60/130,768, filed Apr. 23, 1999, entitled“COMPOSITION FOR PROVIDING AN ABRASION RESISTANT COATING ON A SUBSTRATEWITH A MATCHED REFRACTIVE INDEX: 2,” the contents of which are herebyexpressly incorporated in their entirety by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to coating compositions and methods ofmaking and using same, and more particularly but not by way oflimitation, to coating compositions which, when cured, providesubstantially transparent coatings having abrasion resistance and amatched refractive index to that of the substrate.

The present invention also relates to liquid coating compositions andmethods of making and using same having improved abrasion resistance andimproved stability wherein the liquid coating compositions are derivedfrom aqueous-organic solvent mixtures containing effective amounts of anepoxy-functional silane, colloidal metal oxide composite, atetrafunctional silane, and colloidal silica.

2. Description of Prior Art

Silica based coatings deposited on plastic materials are useful fortheir abrasion resistance and weatherability and thus extend the useablelife of the plastic material. These coatings, in most cases, do notmatch the refractive index of the plastic material and allow forinterference patterns to arise due to the refractive index mismatchbetween the cured coating film and the plastic substrate material. Thismismatch leads to increased reflectivity of the coated plastic materialand to exacerbation of material flaws due to the increased reflectivity.

BRIEF SUMMARY OF THE INVENTION

The present invention provides compositions having improved stabilitywhich, when applied to a variety of substrates and cured, formtransparent coatings having abrasion resistant properties and a matchedrefractive index to that of the substrate as well as methods of makingand using said coating compositions.

Broadly, the coating compositions of the present invention comprise anaqueous-organic solvent mixture containing from about 10 to about 90weight percent, based on the total solids of the composition, of amixture of hydrolysis products and partial condensates of anepoxy-functional sijane, from about 1 to about 90 weight percent, basedon the total weight of the composition, of a carboxylic acid functionalcompound selected from the group consisting of carboxylic acids,multifunctional carboxylic acids, anhydrides, and combinations thereof,from about 1 to 90 weight percent, based on the total solids of thecomposition, of a metal oxide composite colloid, from about 1 to 75weight percent, based on the total solids of the composition, of acolloidal silica material, and from about 1 to 75 weight percent, basedon the total solids of the composition, of a tetrafunctional silane.

The coating compositions of the present invention may further includefrom about 0.1 to about 50 weight percent of a mixture of hydrolysisproducts and partial condensates of one or more silane additives, basedon the total solids of the composition.

It is an object of the present invention to provide coating compositionshaving improved stability, which form transparent coatings upon curing.It is a further object of the present invention to provide stablecoating compositions, which form transparent coatings upon curing whichhave improved adhesion properties, improved resistance to crackformation, and a matched refractive index to that of the substrate.

Other objects, advantages and features of the present invention willbecome apparent upon reading the following detailed description inconjunction with the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description. The invention is capable of otherembodiments or of being practiced or carried out in various ways. Also,it is to be understood that the phraseology and terminology employedherein is for the purpose of description and should not be regarded aslimiting.

The present invention relates to coating compositions having improvedstability which, when applied to a variety of substrates and cured, formsubstantially transparent abrasion resistant coatings which possessimproved adhesion, improved resistance to crack formation, and have amatched refractive index to that of the substrate.

For measuring the refractive indexes of the cured coating compositions,each composition was applied to a cleanly etched lead-silicate glassplaque by dip coating at 2 inches per minute and curing for a period of1 hour at 120° C. The refractive indexes were measured using a Bauschand Lomb Abbe-3L refractometer. Either diiodomethane or1-bromonaphthalene was used as the contact liquid. The standardprocedures for measurement and instrument maintenance contained in theoperator's manual for the Bausch and Lomb Abbe-3L refractometer wereused for data gathering and processing. For testing coated samples,coating compositions were applied to ADC lenses and cured at atemperature in the range from 95° C. to 120° C. for a period of 3 hours.Semi-quantitative assessments of the extent of cracking and adhesionwere made using the following tests. For testing adhesion of the coatedarticles the procedures of ASTM D-3359, i.e. the tape test, werefollowed.

A typical test for cracking and adhesion consists of immersion of thecoated article in boiling water or boiling tap water tint for a periodof time, e. g. 30 minutes, followed by inspection for crack formationand testing for adhesion. Specifically, lenses were tested in BPI BlackTint (Brain Power, Inc.) under boiling conditions. In this test a bottleof BPI tint (approximately 100 grams) was diluted to about 900 gramswith tap water and brought to a boil. The coated article was immersed inthe boiling solution for a period of 30 minutes. The coated article wasremoved from the tint solution and inspected for cracking and tested foradhesion.

For testing abrasion resistance of coated substrates, any of a number ofquantitative test methods may be employed, including the Taber Test(ASTM D-4060), the Tumble Test and Standard Method for the ModifiedBayer Test, which is described in The AR Council of America StandardTesting Procedures section 5.2.5 and is a variation of the test method,ASTM F735-81. In addition, there are a number of qualitative testmethods that may be used for measuring abrasion resistance, includingthe Steel Wool Test and the Eraser Test. In the Steel Wool Test and theEraser Test, sample coated substrates are scratched under reproducibleconditions (constant load, frequency, etc.). The scratched test samplesare then compared and rated against standard samples. Asemi-quantitative application of these test methods involves the use ofan instrument, such as a Spectrophotometer or a Colorimeter, formeasuring the scratches on the coated substrate as a haze gain.

The measured abrasion resistance of a cured coating on a substrate,whether measured by the Modified Bayer Test, Taber Test, Steel WoolTest, Eraser Test, Tumble Test, etc. is a function, in part, of the curetemperature and cure time. In general, higher temperatures and longercure times result in higher measured abrasion resistance. Normally, thecure temperature and cure time are selected for compatibility with thesubstrate; although, sometimes less than optimum cure temperatures andcure times are used due to process and/or equipment limitations. It willbe recognized by those skilled in the art that other variables, such ascoating thickness and the nature of the substrate, will also have aneffect on the measured abrasion resistance. In general, for each type ofsubstrate and for each coating composition there will be an optimumcoating thickness. The optimum cure temperature, cure time, coatingthickness, and the like, can be readily determined empirically by thoseskilled in the art.

In the test method employed to determine the abrasion resistance of thecoating compositions of the present invention, a commercially availablealundum (grain code 1524, 12 grit, alundum ZF) sold by Norton AdvancedCeramics of Canada Inc., 8001 Daly Street, Niagara Falls, Ontario, wasused as the abrasive material. In this test, 540 grams alundum wasloaded into a 9{fraction (5/16)}″×6 ¾″ cradle fitted with four lenses.Each set of four lenses, typically two poly(diethylene glycol-bis-allylcarbonate) lenses, herein referred to as ADC lenses, and two coatedlenses, were subjected to a 4 inch stroke (the direction of the strokecoinciding with the 9{fraction (5/16)}″ length of the cradle) at anoscillation frequency of 300 strokes per minute for a total of 4minutes. The lens cradle was repositioned by turning 180 degrees afterthe initial 2 minutes of oscillations. Repositioning of the cradle wasused to reduce the impact of any inconsistencies in the oscillatingmechanism. The ADC reference lenses used were Silor 70 mm plano FSVlenses, purchased through Essilor of America, Inc. of St. Petersburg,Fla. The above described procedure is slightly modified from that whichis described by the AR Council of America by increasing the weight ofthe alundum to accommodate the increased surface area of the largercradle. The cradle described above holds 4 lenses. The haze generated onthe lenses was then measured on a Gardner XL-835 Colorimeter. The hazegain for each lens was determined as the difference between the initialhaze on the lenses and the haze after testing. The ratio of the hazegain on the ADC reference lenses to the haze gain on the coated samplelenses was then reported as the resultant abrasion resistance of thecoating material. A ratio of greater than 1 indicates a coating whichprovides greater abrasion resistance than the uncoated ADC referencelenses. This ratio is commonly referred to as the Bayer ratio, number orvalue. Coatings with high abrasion resistance possess larger Bayernumbers than coatings with lower abrasion resistance.

It should be understood that: (a) the descriptions herein of coatingsystems which contain epoxy-functional silanes, tetrafunctional silanes,silane additives which do not contain an epoxy-functional group, and thecarboxylic acid component, refer to the incipient silanes and carboxylicacid components from which the coating system is formed, (b) when theepoxy-functional silanes, tetrafunctional silanes, and silane additiveswhich do not contain an epoxy-functional group, are combined with theaqueous-organic solvent mixture under the appropriate conditions, ahydrolysis reaction occurs resulting in partially or fully hydrolyzedspecies, (c) the resultant fully or partially hydrolyzed species cancombine to form mixtures of multifunctional oligomeric siloxane species,(d) the oligomeric siloxane species may or may not contain pendanthydroxy and pendant alkoxy moieties and will be comprised of asilicon-oxygen matrix which contains both silicon-oxygen siloxanelinkages and silicon-oxygen carboxylic acid component linkages, (e) theresultant mixtures are dynamic oligomeric suspensions that undergostructural changes which are dependent upon a multitude of factorsincluding; temperature, pH, water content, catalyst concentration, andthe like.

The coating compositions of the present invention comprise anaqueous-organic solvent mixture containing from about 10 to about 90weight percent, based on the total solids of the composition, of amixture of hydrolysis products and partial condensates of anepoxy-functional silane, from about 1 to about 90 weight percent, basedon the total weight of the composition, of a carboxylic acid functionalcompound selected from the group consisting of carboxylic acids,multifunctional carboxylic acids, anhydrides, and combinations thereof,from about 1 to 90 weight percent, based on the total solids of thecomposition, of a metal oxide composite colloid, from about 1 to 75weight percent, based on the total solids of the composition, of acolloidal silica material, and from about 1 to 75 weight percent, basedon the total solids of the composition, of a tetrafunctional silane.

The amount of epoxy-functional silane, carboxylic acid component, metaloxide composite sol, colloidal silica, and tetrafunctional silaneemployed can vary widely and will generally be dependent upon theproperties desired in the coating composition and the cured coating, aswell as the end use of the substrate to which the coating composition isapplied. Generally, however, desirable results can be obtained where themolar ratio of the epoxy-functional silane component to the colloidalsilica component, tetrafunctional silane component, and the colloidalmetal oxide component are present in the coating composition at a ratioof from about 0.05:1 to 2:1, the molar ratio of the colloidal silicacomponent to the metal oxide composite colloid present in the coatingcomposition is present in a range of from about 0.01:1 to about 50:1,and the molar ratio of the tetrafunctional silane component to the metaloxide composite colloid present in the coating composition is present ina range of from about 0.01 to 1 to about 50:1.

While the presence of water in the aqueous-organic solvent mixture isnecessary to form hydrolysis products of the silane components of themixture, the actual amount of water can vary widely. However, asufficient amount of water must be present in the aqueous-organicsolvent mixture to provide a substantially homogeneous coating mixtureof hydrolysis products and partial condensates of the alkoxy functionalsilanes (i.e., the epoxy-functional silane and other silane additivecomponents) which, when applied and cured on an article, provides asubstantially transparent coating. Such coatings can be obtained byemploying a stoichiometric amount of water, e.g., as required for thehydrolysis of the sum of the hydrolyzable alkoxy groups on the alkoxysilane components in the coating mixture. The abrasion resistance of thecoated article is affected by the concentration of water in theincipient coating mixture, as well as the presence and concentration ofa condensation catalyst.

For example, coating mixtures which contain a low concentration of water(e.g. a stoichiometric concentration of water) require a optionalmineral acid hydrolysis co-catalyst to ensure sufficient hydrolysisnecessary for the formation of a homogeneous coating mixture and acondensation catalyst to obtain coating compositions which possess thedesired abrasion resistance properties after curing. It is preferredthat the amount of water present in the aqueous-organic solvent mixturewill range from about 1 to about 10 equivalents of water for eachhydrolyzable alkoxy group. The effective amount of water and theeffective amount and type of catalyst can be determined empirically.

The solvent constituent of the aqueous-organic solvent mixture of thecoating compositions of the present invention can be any solvent orcombination of solvents which is compatible with the epoxy-functionalsilane, the carboxylic acid component, the colloidal metal oxidecomponent, the colloidal silica component, and the tetrafunctionalsilane component. For example, the solvent constituent of theaqueous-organic solvent mixture may be an alcohol, an ether, a glycol ora glycol ether, a ketone, an ester, a glycolether acetate and mixturesthereof. Alcohols which can be employed as the solvent constituent arerepresented by the formula ROH where R is an alkyl group containing from1 to about 10 carbon atoms. Examples of alcohols which can be employedas the solvent constituent of the aqueous-organic solvent mixtureemployed in the practice of the present invention are methanol, ethanol,propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiarybutanol, cyclohexanol, pentanol, octanol, decanol, and mixtures thereof.

Glycols, ethers, and glycol ethers which can be employed as the solventconstituent of the aqueous-organic solvent mixture are represented bythe formula R¹—(OR²)_(x)—OR¹ where x is 0, 1, 2, 3 or 4, R¹ is hydrogenor an alkyl group containing from 1 to about 10 carbon atoms and R² isan alkylene group containing from 1 to about 10 carbon atoms andcombinations thereof.

Examples of glycols, ethers and glycol ethers having the above-definedformula and which may be used as the solvent constituent of theaqueous-organic solvent mixture of the coating compositions of thepresent invention are di-n-butylether, ethylene glycol dimethyl ether,propylene glycol dimethyl ether, propylene glycol methyl ether,dipropylene glycol methyl ether, tripropylene glycol methyl ether,dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether,ethylene glycol butyl ether, diethylene glycol butyl ether, ethyleneglycol dibutyl ether, ethylene glycol methyl ether, diethylene glycolethyl ether, diethylene glycol dimethyl ether, ethylene glycol ethylether, ethylene glycol diethyl ether, ethylene glycol, diethyleneglycol, triethylene glycol, propylene glycol, dipropylene glycol,tripropylene glycol, butylene glycol, dibutylene glycol, tributyleneglycol and mixtures thereof. In addition to the above, cyclic etherssuch as tetrahydrofuran and dioxane are suitable ethers for theaqueous-organic solvent mixture.

Examples of ketones suitable as the organic solvent constituent of theaqueous-organic solvent mixture are acetone, diacetone alcohol, methylethyl ketone, cyclohexanone, methyl isobutyl ketone and mixturesthereof.

Examples of esters suitable as the organic solvent constitutent of theaqueous-organic solvent mixture are ethyl acetate, n-propyl acetate,n-butyl acetate and combinations thereof.

Examples of glycolether acetates suitable as the organic solventconstituent of the aqueous-organic solvent mixture are propylene glycolmethyl ether acetate, dipropylene glycol methyl ether acetate, ethyl3-ethoxypropionate, ethylene glycol ethyl ether acetate and combinationsthereof.

The epoxy-functional silane useful in the formulation of the coatingcompositions of the present invention can be any epoxy-functional silanewhich is compatible with the carboxylic acid component, the metal oxidecomposite colloid, the colloidal silica components, and thetetrafunctional silane component of the coating composition, and whichprovides a coating composition which, upon curing, produces asubstantially transparent, abrasion resistant coating which exhibitsimproved adhesion and improved resistance to crack formation and whichpossesses a refractive index substantially corresponding to therefractive index of the substrate on which the coating composition isapplied. Generally, such epoxy-functional silanes are represented by theformula R³ _(x)Si(OR⁴)_(4−x) where x is an integer of 1, 2 or 3, R³ isH, an alkyl group, a functionalized alkyl group, an alkylene group, anaryl group, an alkyl ether, and combinations thereof containing from 1to about 10 carbon atoms and having at least 1 epoxy-functional group,and R⁴ is H, an alkyl group containing from 1 to about 5 carbon atoms,an acetyl group, a —Si(OR⁵)_(3−y)R⁶ _(y) group where y is an integer of0, 1, 2, or 3, and combinations thereof where R⁵ is H, an alkyl groupcontaining from 1 to about 5 carbon atoms, an acetyl group, or another—Si(OR⁵)_(3−y)R⁶ _(y) group and combinations thereof, and R⁶ is H, analkyl group, a functionalized alkyl group, an alkylene group, an arylgroup, an alkyl ether, and combinations thereof containing from 1 toabout 10 carbon atoms which may also contain an epoxy-functional group.

Examples of such epoxy-functional silanes are glycidoxymethyltrimethoxysilane, 3-glycidoxypropyltrihydroxysilane,3-glycidoxypropyldimethylhydroxysilane,3-glycidoxypropyltrimeth-oxysilane, 3-glycidoxypropyltriethoxysilane,3-glycidoxypropyl-dimethoxymethylsilane,3-glycidoxypropyldimethylmethoxysilane,3-glycidoxypropyltributoxysilane,1,3-bis(glycidoxypropyl)tetramethyldisiloxane,1,3-bis(glycidoxypropyl)tetramethoxydisiloxane,1,3-bis(glycidoxypropyl)-1,3-dimethyl-1,3-dimethoxydisiloxane,2,3-epoxypropyltrimethoxysilane, 3,4-epoxybutyltrimethoxysilane,6,7-epoxyheptyltrimethoxysilane, 9,10-epoxydecyltrimethoxysilane,1,3-bis(2,3-epoxypropyl)tetramethoxydisiloxane,1,3-bis(6,7-epoxyheptyl)tetramethoxydisiloxane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and the like.

The coating compositions of the present invention contain any carboxylicacid component compatible with the epoxy-functional silane, thecolloidal metal oxide component, the colloidal silica component, and thetetrafunctional silane. The carboxylic acid component is capable ofinteracting with the hydrolysis products and partial condensates of theepoxy-functional silane and the tetrafunctional silane to provide acoating composition which, upon curing, produces a substantiallytransparent, abrasion resistant coating having improved adhesion andimproved crack resistance and which possesses a refractive indexsubstantially corresponding to the refractive index of the substrate onwhich the coating composition is applied.

Carboxylic acid component as used herein is understood to include mono-and multi-functional carboxylic acids as well as anhydrides, whichproduce mono- and multi-functional carboxylic acids. Examples ofcarboxylic acids which can be in the coating compositions of the presentinvention include acetic acid, acrylic acid, methacrylic acid, formicacid, propionic acid, butanoic acid, benzoic acid, malic acid, aconiticacid (cis,trans), itaconic acid, succinic acid, malonic acid, glutaricacid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacicacid, cyclohexyl succinic acid, 1,3,5 benzene tricarboxylic acid,1,2,4,5 benzene tetracarboxylic acid, 1,4-cyclohexanedicarboxylic acid,1,3-cyclohexanedicarboxylic acid, 1,1-cyclohexanediacetic acid,1,3cyclohexanediacetic acid, 1,3,5-cyclohexanetricarboxylic acid andunsaturated dibasic acids such as fumaric acid and maleic acid andcombinations thereof.

Examples of anhydrides which can be employed to produce the carboxylicacid component of the coating compositions of the present inventioninclude the anhydrides of the above mentioned carboxylic acids such asacetic anhydride, propionic anhydride, acrylic anhydride, methacrylicanhydride and the cyclic anhydrides of the above mentioned dibasic acidssuch as succinic anhydride, itaconic anhydride, glutaric anhydride,trimellitic anhydride, pyromellitic anhydride, phthalic anhydride andmaleic anhydride and combinations thereof.

Optionally, in addition to the carboxylic acid component of the coatingcomposition, a mineral acid such as, for example, hydrochloric acid ornitric acid, can be used as a co-hydrolysis catalyst for the hydrolysisof the silane compounds described herein.

The metal oxide colloidal component of the present invention may consistof a single component metal oxide colloid or a complex composite metaloxide colloid consisting of more than one metal oxide component. Therefractive index of the colloidal metal oxide component should besufficiently higher than the coating mixture so the addition ofeffective amounts of the colloidal metal oxide component can yield adesirable refractive index for the entire coating composition. Thecolloidal metal oxide component may contain any combination of titania,zirconia, tin oxide, antimony oxide, iron oxide, lead oxide, and/orbismuth oxide for purposes of increasing the refractive index. Thecolloidal metal oxide component may also contain alumina and/or silica.In general, it is preferred that the colloidal metal oxide componentused in the present invention consist of a composite mixture of two ormore metal oxide components listed above where at least one of the metaloxide components present in the composite mixture is neither alumina norsilica.

Examples of commercially available metal oxide colloidal materials andcomposite metal oxide component materials are the Suncolloid seriesAMT-130S, HIS-33M, HIT-30M, and HIT-32M from Nissan Chemical IndustriesLTD., Optolake 1130F-2(A-8), 2130F-2(A-8), Optolake ARC-7, and QueenTitanic-11-1 from Catalyst and Chemical Industries LTD. Proper selectionof the amounts and type of the colloidal metal oxide component, theepoxy-functional silane, the carboxylic acid component, the colloidalsilica component, the tetrafunctional silane component, and optionallyif desired, the optional silane component and condensation catalyst willyield a cured coating material with a refractive index in the range from1.4 to greater than 1.7 refractive index units.

The colloidal silica component of the present invention can be either anaqueous or non-aqueous based material. The colloidal silica is anaqueous or non-aqueous solvent dispersion of particulate silica and thevarious products differ principally by particle size, silicaconcentration, pH, presence of stabilizing ions, solvent makeup, and thelike. Colloidal silica is commercially available under a number ofdifferent tradename designations, including Nalcoag® (Nalco ChemicalCo., Naperville, Ill.); Nyacol® (Nyacol Products, Inc., Ashland, Mass.);Snowtex® (Nissan Chemical Industries, LTD., Tokyo, Japan); Ludox®(DuPont Company, Wilmington, Del.); and Highlink OG® (Hoechst Celanese,Charlotte, N.C.). It should be noted that substantially differentproduct properties can be obtained through the selection of differentcolloidal silicas.

Colloids which possess acidic pH values and very slightly basic pHvalues with low levels of sodium are preferred. These colloidal silicamaterials provide an increase in the abrasion resistance and provide aresistance to crack formation, which can result from exposure of thecured coatings to boiling tap water tint baths, vide supra. Examples ofpreferred colloidal silica materials are Nalco® 1042 and Nalco® 1040 andthe like. Basic colloidal silica materials which possess higher pHvalues and/or a higher concentration of sodium ions result in curedcoating compositions which possess abrasion resistance which is lowerthan that which results from the use of the preferred colloidal silicamaterials and are not preferred. An example of a material, which is notpreferred is Nalco® 1115 and the like.

The tetrafunctional silanes useful in the formulation of the coatingcompositions of the present invention are represented by the formulaSi(OR⁷)₄ where R⁷ is H, an alkyl group containing from 1 to about 5carbon atoms and ethers thereof, an (OR⁷) carboxylate, a —Si(OR⁸)₃ groupwhere R⁸ is a H, an alkyl group containing from 1 to about 5 carbonatoms and ethers thereof, an (OR⁷) carboxylate, or another —Si(OR⁸)₃group and combinations thereof. Examples of tetrafunctional silanesrepresented by the formula Si(OR⁷)₄ are tetramethyl orthosilicate,tetraethyl orthosilicate, tetrapropyl orthosilicate, tetraisopropylorthosilicate, tetrabutyl ortho-silicate, tetraisobutyl orthosilicate,tetrakis(methoxyethoxy) silane, tetrakis(methoxypropoxy)silane,tetrakis(ethoxyethoxy) silane, tetrakis(methoxyethoxyethoxy)silane,trimethoxyethoxy-silane, dimethoxydiethoxysilane,triethoxymethoxysilane, poly-(dimethoxysiloxane),poly(diethoxysiloxane), poly(dimethoxy-diethoxysiloxane),tetrakis(trimethoxysiloxy)silane, tetrakis-(triethoxysiloxy)silane, andthe like. In addition to the R⁷ and R⁸ substituants described above forthe tetrafunctional silane, R⁷ and R⁸ taken with oxygen (OR⁷) and (OR⁸)can be carboxylate groups. Examples oftetrafunctional silanes withcarboxylate function-alities are silicon tetracetate, silicontetrapropionate and silicon tetrabutyrate.

The coating compositions of the present invention are also stable withrespect to aging, both in terms of performance and solution stability.The aging of the coating compositions is characterized by a gradualincrease in viscosity, which eventually renders the coating compositionsunusable due to processing constraints. The coating compositions of thepresent invention, when stored at temperatures of 5° C. or lower haveusable shelf lives of 3-4 months. During this period, the abrasionresistance of the cured coatings does not significantly decrease withtime. The abrasion resistant coating compositions which provide indexmatching properties described in the present invention are achievedthrough the unique combination of an epoxy-functional silane, acarboxylic acid component, a composite metal oxide colloid, a colloidalsilica component, and a tetrafunctional silane. The coating compositionsmay optionally include other materials which may: (a) enhance thestability of the coating compositions; (b) increase the abrasionresistance of cured coatings produced by the coating compositions; (c)improve processing of the coating compositions; and (d) provide otherdesirable properties to the coating composition and the cured product ofthe coating compositions.

The coating compositions of the present invention may further includefrom about 0.1 to about 50 weight percent, based on the weight oftotalsolids of the coating compositions, of a mixture of hydrolysis productsand partial condensates of one or more silane additives (i.e,trifunctional silanes, difunctional silanes, monofunctional silanes, andmixtures thereof). The selection of the silane additives incorporatedinto the coating compositions of the present invention will depend uponthe particular properties to be enhanced or imparted to either thecoating composition or the cured coating composition. The silaneadditives are represented by the formula R⁹ _(x)Si(OR¹⁰)_(4−x) where xis a 1, 2 or 3; R⁹ is H, or an alkyl group containing from 1 to about 10carbon atoms, a functionalized alkyl group, an alkylene group, an arylgroup an alkyl ether group and combinations thereof; R¹⁰ is H, an alkylgroup containing from 1 to about 10 carbon atoms, an acetyl group, a—Si(OR¹⁰)₃ group and combinations thereof.

Examples of silane additives represented by the above-defined formulaare methyltrimethoxysilane, ethyltrimethoxysilane,propyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane,hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane,cyclohexyltrimethoxysilane, cyclohexylmethyltrimethoxysilane,3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane,allyltrimethoxysilane, dimethyldimethoxysilane,2-(3-cyclohexenyl)ethyltrimethoxysilane, 3-cyanopropyltrimethoxysilane,3-cyanopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane,2-chloroethyltrimethoxysilane, phenethyltrimethoxysilane,3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane,phenyltrimethoxysilane, 3-isocyanopropyltrimethoxysilane,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,4-(2-aminoethylaminomethyl)phenethyltrimethoxysilane,chloromethyltriethoxysilane, 2-chloroethyltriethoxysilane,3-chloropropyltriethoxysilane, phenyltriethoxysilane,ethyltriethoxysilane, propyltriethoxysilane, butyltriethoxysilane,isobutyltriethoxysilane, hexyltriethoxysilane, octyltriethoxysilane,decyltriethoxysilane, cyclohexyltriethoxysilane,cyclohexylmethyltriethoxysilane, 3-methacryloxypropyltriethoxysilane,vinyltriethoxysilane, allyltriethoxysilane,[2-(3-cyclohexenyl)ethyltriethoxysilane, 3 cyanopropyltriethoxysilane,3-methacrylamidopropyltriethoxysilane, 3-ethoxypropyltrimethoxysilane,3-ethoxypropyltrimethoxysilane, 3-propoxypropyltrimethoxysilane,3-methoxyethyltrimethoxysilane, 3-ethoxyethyltrimethoxysilane,3-propoxyethyltrimethoxysilane,2-[methoxy(polyethyleneoxy)propyl]heptamethyltrisiloxane, [methoxy(polyethyleneoxy)propyl]trimethoxysilane,[methoxy(polyethylene-oxy)ethyl]trimethoxysilane,[methoxy(polyethyleneoxy)propyl]-triethoxysilane,[methoxy(polyethyleneoxy)ethyl]triethoxysilane, and the like.

Although a condensation catalyst is not an essential ingredient of thecoating compositions of the present invention, the addition of acondensation catalyst can affect abrasion resistance and otherproperties of the coating including stability, tinting capacity,porosity, cosmetics, caustic resistance, water resistance and the like.When employing a condensation catalyst, the amount of catalyst used canvary widely, but will generally be present in an amount from about 0.05to about 20 weight percent, based on the total solids of thecomposition.

Examples of catalysts which can be incorporated into the coatingcompositions of the present invention are (i) metal acetylacetonates,(ii) diamides, (iii) imidazoles, (iv) amines and ammonium salts, (v)organic sulfonic acids and their amine salts, (vi) alkali metal salts ofcarboxylic acids, (vii) alkali metal hydroxides, (viii) fluoride salts,and (ix) organostannanes. Thus, examples of such catalysts include forgroup (i) such compounds as aluminum, zinc, iron and cobaltacetylacetonates; group (ii) dicyandiamide; for group (iii) suchcompounds as 2-methylimidazole, 2-ethyl-4 methylimidazole and1-cyanoethyl-2-propylimidazole; for group (iv), such compounds asbenzyldimethylamine, and 1,2-diaminocyclohexane; for group (v), suchcompounds as trifluoromethanesulfonic acid; for group (vi), suchcompounds as sodium acetate, for group (vii), such compounds as sodiumhydroxide, and potassium hydroxide, for group (viii), tetra n-butylammonium fluoride, and for group (ix), dibutyltin dilaurate, and thelike.

An effective amount of a leveling or flow control agent can beincorporated into the composition to more evenly spread or level thecomposition on the surface of the substrate and to provide substantiallyuniform contact with the substrate. The amount of the leveling or flowcontrol agent can vary widely, but generally is an amount sufficient toprovide the coating composition with from about 10 to about 50,000 ppmof the leveling or flow control agent. Any conventional, commerciallyavailable leveling or flow control agent which is compatible with thecoating composition and the substrate and which is capable of levelingthe coating composition on a substrate and which enhances wettingbetween the coating composition and the substrate can be employed. Theuse of leveling and flow control agents is well known in the art and hasbeen described in the “Handbook of Coating Additives” (ed. Leonard J.Calbo, pub. Marcel Dekker), pg 119-145.

Examples of such leveling or flow control agents which can beincorporated into the coating compositions of the present inventioninclude organic polyethers such as TRITON X-100, X-405, N-57 from Rohmand Haas, silicones such as Paint Additive 3, Paint Additive 29, PaintAdditive 57 from Dow Corning, SILWET L-77, and SILWET L-7600 from OSiSpecialties, and fluorosurfactants such as FLUORAD FC-171, FLUORADFC-430 and FLUORAD FC-431 from 3M Corporation.

In addition, other additives can be added to the coating compositions ofthe present invention in order to enhance the usefulness of the coatingcompositions or the coatings produced by curing the coatingcompositions. For example, ultraviolet absorbers, antioxidants, and thelike can be incorporated into the coating compositions of the presentinvention, if desired.

The coating compositions of the present invention can be prepared by avariety of processes to provide stable coating compositions, which, uponcuring, produce substantially transparent abrasion resistant coatingshaving improved abrasion resistance, resistance to crack formation, anda matched refractive index.

The preferred method for preparing the coating compositions of thepresent invention consists of the initial hydrolysis of theepoxy-functional silane by addition of the silane to a mixture ofdeionized water, the acid component, and the solvent constituent. Aftersufficient time for the hydrolysis, the tetrafunctional silane is addedand the resultant mixture is allowed to stir for a sufficient period oftime to allow for hydrolysis of the tetrafunctional silane. To thismixture colloidal silica is then added followed by slow addition of themetal oxide colloid to insure maximum homogeneity. When desired, acondensation catalyst and/or a surfactant for leveling and flowimprovement may be added to the final coating composition.

The coating compositions of the present invention can be applied tosolid substrates by conventional methods, such as flow coating, spraycoating, curtain coating, dip coating, spin coating, roll coating, etc.to form a continuous surface film. Any substrate compatible with thecompositions can be coated with the compositions, such as plasticmaterials, wood, paper, metal, printed surfaces, leather, glass,ceramics, glass ceramics, mineral based materials and textiles. Thecompositions are especially useful as coatings for synthetic organicpolymeric substrates in sheet or film form, such as acrylic polymers,poly(ethyleneterephthalate), polycarbonates, polyamides, polyimides,copolymers of acrylonitrile-styrene, styrene-acrylonitrile-butadienecopolymers, polyvinyl chloride, butyrates, polyethylene and the like.Transparent polymeric materials coated with these compositions areuseful as flat or curved enclosures, such as windows, liquid crystaldisplay screens, skylights and windshields, especially fortransportation equipment. Plastic lenses, such as acrylic orpolycarbonate ophthalmic lenses, can also be coated with thecompositions of the invention.

By choice of proper formulation, application conditions and pretreatment(including the use of primers) of the substrate, the coatingcompositions of the present invention can be adhered to substantiallyall solid surfaces. Abrasion resistant coatings having improved adhesionand resistance to cracking can be obtained from coating compositions ofthe present invention by heat curing at temperatures in the range offrom about 50° C. to about 200° C. for a period of from about 5 minutesto about 18 hours. The coating thickness can be varied by means of theparticular application technique, but coatings having a thickness offrom about 0.5 to about 20 microns, and more desirably from about 1 toabout 10 microns, are generally utilized.

In order to further illustrate the present invention, the followingexamples are given. However, it is to be understood that the examplesare for illustrative purposes only and are not to be construed aslimiting the scope of the subject invention.

EXAMPLES

Procedure

Etched poly(diethylene glycol-bis-allyl carbonate) lenses and plaques(referred to as ADC lenses or ADC plaques) were use for coating andtesting. The ADC lenses and plaques were etched by contact with a 10%potassium hydroxide solution containing propylene glycol methyl etherand water for a period of about 10 minutes. The lenses and/or plaqueswere coated by dip coating using a specified withdrawal rate in units ofinches per minute (ipm). The lenses and/or plaques were cured at atemperature of 110° C. for 3 hours. The lenses and/or plaques weresubjected to the aforementioned test procedures to determine adhesion,resistance to cracking and abrasion resistance.

Example 1

63.0 grams of 3-glycidoxypropyltrimethoxy silane(GPTMS) were addeddropwise to a solution composed of 92.8 grams of deionized water, 92.8grams of propylene glycol methyl ether (PMOH), and 10.0 grams of aceticacid (AcOH). The aqueous-organic GPTMS mixture was stirred for 1 hour.To the mixture, 19.8 grams of TEOS were added dropwise and allowed tostir overnight. 16.8 grams of Nalco-1042 colloidal silica were addeddropwise and the resulting mixture was stirred for approximately 4hours. 104.7 grams of Optalake 2130f-2 (A-8), a colloidal metal oxide,were added dropwise and the resulting mixture was stirred overnight toyield a coating composition.

1.4 grams of a flow modifier comprising a PMOH-based solution containing10 weight percent FC-430 (3M), were added to 190 grams of a coatingcomposition prepared in accordance with the process described above. Thecoating composition was left to stir for an additional 10 to 30 minutesto insure mixing. This coating composition was applied to etched ADClenses, ADC plaques and 1.7 R₁ plaques, according to the procedureabove, at a withdrawal rate of 2 ipm to provide a cured coating having athickness of about 1.9 microns, a refractive index of about 1.60, and aBayer number of 8.9. After exposure to boiling tap water tint for 15minutes, the coated lenses or plaques did not exhibit any crazing.

Example 2

63.0 grams of GPTMS were added dropwise to a solution composed of 95.5grams of deionized water, 95.5 grams of PMOH, and 10.0 grams of AcOH.The aqueous-organic GPTMS mixture was stirred for 1 hour. To themixture, 19.8 grams of TEOS were added dropwise and allowed to stirovernight. 11.4 grams of Nalco-1050 colloidal silica were added dropwiseand the resulting mixture was stirred for approximately 4 hours. 104.7grams of Optalake 2130f-2 (A-8), a colloidal metal oxide, were addeddropwise and the resulting mixture was stirred overnight to yield acoating composition.

1.4 grams of a flow modifier comprising a PMOH-based solution containing10 weight percent FC-430 (3M), were added to 190 grams of a coatingcomposition prepared in accordance with the process described above. Thecoating composition was left to stir for an additional 10 to 30 minutesto insure mixing. This coating composition was applied to etched ADClenses, ADC plaques and 1.7 R₁ plaques, according to procedure A, at awithdrawal rate of 2 ipm to provide a cured coating having a thicknessof about 2.0 microns, a refractive index of about 1.60, and a Bayernumber of 6.3. After exposure to boiling tap water tint for 15 minutes,the coated lenses or plaques did not exhibit any crazing.

Comparative Ex. A

63.0 grams of GPTMS were added dropwise to a solution composed of 91.3grams of deionized water, 91.3 grams of PMOH, and 10.0 grams of AcOH.The aqueous-organic GPTMS mixture was stirred for 1 hour. To themixture, 39.7 grams of TEOS were added dropwise and allowed to stir for5 hours. 104.7 grams of Optalake 2130f-2 (A-8), a colloidal metal oxide,were added dropwise and the resulting mixture was stirred overnight toyield a coating composition.

1.4 grams of a flow modifier comprising a PMOH-based solution containing10 weight percent FC-430 (3M), were added to 190 grams of a coatingcomposition prepared in accordance with the process described incomparative example A. The coating composition was left to stir for anadditional 10 to 30 minutes to insure mixing. This coating compositionwas applied to etched ADC lenses, ADC plaques and 1.7 R₁ plaques,according to the procedure above, at a withdrawal rate of 2 ipm toprovide a cured coating having a thickness of about 1.9 microns, arefractive index of about 1.60, and a Bayer number of 10.0. Afterexposure to boiling tap water tint for 15 minutes, the coated lenses orplaques exhibited crazing.

Example 3a

26.7 grams of GPTMS were added dropwise to a stirring 49.5 grams ofdeionized water. The aqueous-organic GPTMS mixture was stirred for 1hour. A solution of 4.6 grams of itaconic acid dissolved in 49.5 gramsof PMOH were added quickly to the aqueous GPTMS mixture followed by 30minutes of stirring. 8.4 grams of TEOS were added to the mixture andstirred overnight. To the resultant mixture, 7.1 grams of Nalco-1034Acolloidal silica were added dropwise and allowed to stir forapproximately 4 hours. 44.2 grams of Optalake 2130f-2 (A-8), a colloidalmetal oxide, were added dropwise and the resulting mixture was stirredovernight to yield a coating composition. 0.14 grams of a surfactantsolution, 10% PA-57 in PMOH, were added to the coating composition. Toinsure complete mixing, the coating mixture was stirred for anadditional 10 to 30 minutes. This coating composition was applied toetched ADC lenses, ADC plaques and 1.7 R₁ plaques, according to theprocedure above, at a withdrawal rate of 2 ipm to provide a curedcoating having a thickness of about 2.2 microns, a refractive index ofabout 1.60, and a Bayer number of 5.5.

Example 3b

53.7 grams of GPTMS were added dropwise to a solution composed of 106.5grams of deionized water, 29.4 grams of PMOH, and 9.2 grams of itaconicacid. The aqueous-organic GPTMS mixture was stirred for 1 hour. To themixture, 16.9 grams of TEOS were added and stirred overnight. 14.3 gramsof Nalco-1042 colloidal silica were added dropwise and the resultingmixture was stirred for approximately 4 hours. To this mixture, 89.1grams of Optalake 2130f-2 (A-8), a colloidal metal oxide, were addeddropwise and the resulting mixture was stirred overnight to yield acoating composition. A solution consisting of 3.8 grams of DCDAdissolved in 77.1 grams of PMOH were added to the above coatingcomposition. After stirring for almost one complete day, 23 hours, 0.3grams of a PA-57 solution,10% PA-57 in PMOH, were added to thecomposition and allowed to stir for 10 to 30 minutes. This coatingcomposition was applied to etched ADC lenses, ADC plaques and 1.7 R₁plaques, according to the procedure above, at a withdrawal rate of 2 ipmto provide a cured coating having a thickness of about 2.0 microns, arefractive index of about 1.60, and a Bayer number of 5.7. Afterexposure to boiling tap water tint for 15 minutes, the coated lenses orplaques did not exhibit any crazing.

Comparative Ex. B

26.6 grams of GPTMS were added dropwise to a stirring 40.2 grams ofdeionized water. The aqueous-organic GPTMS mixture was stirred for 1hour. A solution of 4.6 grams of itaconic acid dissolved in 40.2 gramsof PMOH were added quickly to the aqueous GPTMS mixture followed by 30minutes of stirring. 16.8 grams of TEOS were added dropwise and theresulting mixture was stirred overnight. To this mixture, 44.3 grams ofOptalake 2130f-2 (A-8), a colloidal metal oxide, were added dropwise andthe resulting mixture was stirred for an additional 4 hours to yield acoating composition.

Comparative Ex. B1

0.14 grams of a flow modifier comprising a PMOH-based solutioncontaingin 10 weight percent PA-57, were added to 190 grams of thecoating composition, as described in comparative example B. The coatingcomposition was left to stir for an additional 10 to 30 minutes toinsure mixing. This coating composition was applied to etched ADClenses, ADC plaques and 1.7 R₁ plaques, according to the procedureabove, at a withdrawal rate of 2 ipm to provide a cured coating having athickness of about 1.9 microns, a refractive index of about 1.60, and aBayer number of 6.5. After exposure to boiling tap water tint for 10minutes, the coated lenses or plaques exhibited crazing.

Comparative Ex. B2

1.9 grams of DCDA were added to 190.0 grams of the coating composition,as described in comparative example B. The mixture was left to stir forapproximately 4 hours followed by the addition of a 0.14-gram solutionof PA-57, 10 weight percent in PMOH. The coating composition was left tostir for an additional 10 to 30 minutes to insure mixing. This coatingcomposition was applied to etched ADC lenses, ADC plaques and 1.7 R₁plaques, according to the procedure above, at a withdrawal rate of 2 ipmto provide a cured coating having a thickness of about 1.9 microns, arefractive index of about 1.60, and a Bayer number of 7.1. Afterexposure to boiling tap water tint for 15 minutes, the coated lenses orplaques did not exhibit any crazing.

Example 5

56.3 grams of GPTMS were added dropwise to a stirring solution composedof 9.5 grams of 0.05N aqueous HCl solution. The aqueous-organic GPTMSmixture stirred for approximately 30 minutes. A solution of 9.6 grams ofITA dissolved in 203.1 grams of PMOH were added quickly to the mixtureand stirred for an additional 30 minutes. To the mixture, 17.7 grams ofTEOS were added to the mixture and stirred for approximately 5 hours.10.2 grams of Nalco1050 colloidal silica were added dropwise and theresulting mixture was stirred overnight. To this mixture, 93.6 grams ofOptalake 2130f-2 (A-8), a colloidal metal oxide, were added dropwise andthe resulting mixture was stirred for an additional 4 hours to yield acoating composition.

Example 5A

1.4 grams of a flow modifier comprising a PMOH-based solution containing10 weight percent FC-430 (3M), were added to 190 grams of a coatingcomposition prepared in accordance with the process described in Example5. The coating composition was left to stir for an additional 10 to 30minutes to insure mixing. This coating composition was applied to etchedADC lenses, ADC plaques and 1.7 R₁ plaques, according to the procedureabove, at a withdrawal rate of 2 ipm to provide a cured coating having athickness of about 1.7 microns, a refractive index of about 1.61, and aBayer number of 2.3. After exposure to boiling tap water tint for 15minutes, the coated lenses or plaques did not exhibit any crazing.

Example 5B

1.9 grams of DCDA were added to 188.1 grams of the coating composition,as described in Example 5, followed by a dilution with 7.3 grams of a 50weight percent solution of PMOH in deionized water. The mixture was leftto stir overnight followed by the addition of a 1.4 gram solution ofFC-430 (3M), 10 weight percent in PMOH. The coating composition was leftto stir for an additional 10 to 30 minutes to insure mixing. Thiscoating composition was applied to etched ADC lenses, ADC plaques and1.7 R₁ plaques, according to the procedure above, at a withdrawal rateof 2 ipm to provide a cured coating having a thickness of about 1.5microns, a refractive index of about 1.61, and a Bayer number of 6.2.After exposure to boiling tap water tint for 15 minutes, the coatedlenses or plaques did not exhibit any crazing.

Example 6

56.1 grams of GPTMS were added dropwise to a stirring solution of 9.5grams of a 0.05N aqueous HCl solution. The aqueous-organic GPTMS mixturestirred for approximately 30 minutes. A solution of 9.6 grams of ITAdissolved in 198.9 grams of PMOH were added quickly to the mixture andstirred for an additional 30 minutes. To the mixture, 17.7 grams of TEOSwere added to the mixture and stirred for approximately 4 hours. 15.0grams of Nalco-1042 colloidal silica were added dropwise and theresulting mixture was stirred overnight. To this mixture, 93.3 grams ofOptalake 2130f-2 (A-8), a colloidal metal oxide, were added dropwise andthe resulting mixture was stirred for an additional 4 hours to yield acoating composition. After exposure to boiling tap water tint for 15minutes, the coated lenses or plaques did not exhibit any crazing.

Example 6A

1.4 grams of a flow modifier comprising a PMOH-based solution containing10 weight percent FC-430 (3M), were added to 190 grams of a coatingcomposition prepared in accordance with the process described in Example6. The coating composition was left to stir for an additional 10 to 30minutes to insure mixing. This coating composition was applied to etchedADC lenses, ADC plaques and 1.7 R₁ plaques, according to the procedureabove, at a withdrawal rate of 2 ipm to provide a cured coating having athickness of about 1.3 microns, a refractive index of about 1.61, and aBayer number of 5.0. After exposure to boiling tap water tint for 15minutes, the coated lenses or plaques did not exhibit any crazing.

Example 6B

1.7 grams of DCDA were added to 188.3 grams of the coating composition,as described in example 6, followed by a dilution with 6.0 grams of a 50weight percent solution of PMOH in deionized water. The mixture was leftto stir overnight followed by the addition of a 1.4 gram solution ofFC-430 (3M), 10 weight percent in PMOH. The coating composition was leftto stir for an additional 10 to 30 minutes to insure mixing. Thiscoating composition was applied to etched ADC lenses, ADC plaques and1.7 R₁ plaques, according to the procedure above, at a withdrawal rateof 2 ipm to provide a cured coating having a thickness of about 1.6microns, a refractive index of about 1.61, and a Bayer number of 5.8.After exposure to boiling tap water tint for 15 minutes, the coatedlenses or plaques did not exhibit any crazing.

Comparative Ex. C

63.7 grams of GPTMS were added dropwise to a solution composed of 27.5grams of 0.01N aqueous HCl, 46.9 grams of methanol, 101.9 grams ofmethylethyl ketone, and 12.2 grams of ITA. The aqueous-organic GPTMSmixture was stirred for 1 hour. 56.0 grams of TEOS were added dropwiseand the resulting mixture was stirred overnight. To this mixture, 91.8grams of Optalake 1130F-2(A-8), a colloidal metal oxide, were addeddropwise and the resulting mixture was stirred for an additional 7 hoursto yield a coating composition.

Comparative Ex. C1

0.95 grams of L-77 were added to 190 grams of the coating composition,as described in comparative example C. The coating composition was leftto stir for an additional 10 to 30 minutes to insure mixing. Thiscoating composition was applied to etched ADC lenses, ADC plaques and1.7 R₁ plaques, according to the procedure above, at a withdrawal rateof 2 ipm to provide a cured coating having a thickness of about 1.3microns, a refractive index of about 1.61, and a Bayer number of 4.0.After exposure to boiling tap water tint for 10 minutes, the coatedlenses or plaques exhibited crazing.

Comparative Ex. C2

2.4 grams of DCDA were added to 187.6 grams of the coating composition,as described in comparative example C. The mixture was left to stirovernight followed by the addition of 0.96 grams of L-77. The coatingcomposition was left to stir for an additional 10 to 30 minutes toinsure mixing. This coating composition was applied to etched ADClenses, ADC plaques and 1.7 R₁ plaques, according to the procedureabove, at a withdrawal rate of 2 ipm to provide a cured coating having athickness of about 1.4 microns, a refractive index of about 1.60, and aBayer number of 7.6. After exposure to boiling tap water tint for 10minutes, the coated lenses or plaques exhibited crazing.

Comparative Ex. D

A stirred mixture of 63.6 grams of GPTMS and 56.0 grams of TEOS wereadded dropwise to 27.5 grams of a 0.01N HCl solution. Stirring proceededfor approximately 1 hour followed by the addition of a solvent mixtureof 46.9 grams of methanol and 101.9 grams of methylethyl ketone. Afterthe mixture was stirred for 1 hour, the resulting composition was agedin the cold room, 4 C, for approximately 24 hours. To this mixture, 91.8grams of Optalake 1130F-2(A-8) a colloidal metal oxide, were addeddropwise and the resulting mixture was stirred overnight. 12.2 grams ofITA were added to the mixture and stirred for an additional hour toyield a coating composition.

Comparative Ex. D1

0.95 grams of L-77 were added to 190 grams of the coating composition,as described in comparative example D. The coating composition was leftto stir for an additional 10 to 30 minutes to insure mixing. Thiscoating composition was applied to etched ADC lenses, ADC plaques and1.7 R₁ plaques, according to the procedure above, at a withdrawal rateof 2 ipm to provide a cured coating having a thickness of about 1.2microns, a refractive index of about 1.61, and a Bayer number of 4.6.After exposure to boiling tap water tint for 10 minutes, the coatedlenses or plaques exhibited crazing.

Comparative Ex. D2

2.4 grams of DCDA were added to 187.6 grams of the coating composition,as described in comparative example D. The mixture was left to stir for1 hour followed by the addition of 0.96 grams of L-77. The coatingcomposition was left to stir for an additional 10 to 30 minutes toinsure mixing. This coating composition was applied to etched ADClenses, ADC plaques and 1.7 R₁ plaques, according to the procedureabove, at a withdrawal rate of 2 ipm to provide a cured coating having athickness of about 1.5 microns, a refractive index of about 1.60, and aBayer number of 6.0. After exposure to boiling tap water tint for 10minutes, the coated lenses or plaques exhibited light crazing.

Thus, it should be apparent that there has been provided in accordancewith the present invention a coating composition and a method for makingand using same that fully satisfy the objectives and advantages setforth above. Although the invention has been described in conjunctionwith specific embodiments thereof, it is evident that many alternatives,modifications and variations will be apparent to those skilled in theart. Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. Changes may be made in the construction and theoperation of the various components, elements and assemblies describedherein and changes may be made in the steps or the sequence of steps ofthe methods described herein without departing from the spirit and scopeof the invention as defined in the following claims.

What is claimed is:
 1. A coating composition which, when applied to asubstrate and cured, provides an abrasion resistant coating on thesubstrate and has a refractive index, comprising: an aqueous organicsolvent mixture containing hydrolysis products and partial condensatesof an epoxy functional silane, a colloidal silica material, a metaloxide composite colloid, a tetrafunctional silane, and a carboxylic acidfunctional compound, wherein the carboxylic acid functional compound isselected from the group consisting of monofunctional carboxylic acids,multifunctional carboxylic acids, anhydrides, and combinations thereof,the epoxy functional silane is present in a molar ratio to the colloidalsilica component, the tetrafunctional silane component, and the metaloxide composite colloid component of from about 0.05:1 to 2:1 and themolar ratio of the colloidal silica component and the tetrafunctionalsilane component to the metal oxide composite colloid component is fromabout 0.01:1 to about 50:1; and an effective amount of a leveling agentthereby spreading the aqueous-organic solvent mixture on the substrateto provide substantially uniform contact of the aqueous-organic solventmixture with the substrate.
 2. The coating composition of claim 1,wherein the hydrolysis products and partial condensates of the epoxyfunctional silane are present in the aqueous-organic solvent mixture inan amount from about 10 to about 90 weight percent, based on the totalsolids of the composition.
 3. The coating composition of claim 1,wherein the carboxylic acid functional compound is present in theaqueous-organic solvent mixture in an amount of from about 1 to 90weight percent, based on the total weight of the composition.
 4. Thecoating composition of claim 1, wherein the colloidal silica componentis present in the aqueous-organic solvent mixture in an amount of fromabout 0.1 to 70 weight percent, based on the total solids of thecomposition.
 5. The coating composition of claim 1, wherein the metaloxide composite colloid component is present in the aqueous-organicsolvent mixture in an amount of from about 0.1 to 80 weight percent,based on the total solids of the composition.
 6. The coating compositionof claim 1, wherein the tetrafunctional silane component is present inthe aqueous-organic solvent mixture from about 0.1 to 70 weight percent,based on the total solids of the composition.
 7. The coating compositionof claim 1, wherein the solvent constituent of the aqueous-organicsolvent mixture is selected from the group consisting of an alcohol, anether, a glycol ether, an ester, a ketone, a glycolether acetate andcombinations thereof.
 8. The coating composition of claim 1, wherein thesolvent constituent of the aqueous-organic solvent mixture is an alcoholhaving the general formula ROH, where R is an alkyl group containingfrom about 1 to about 10 carbon atoms.
 9. The coating composition ofclaim 1, wherein the solvent constituent of the aqueous-organic solventmixture is selected from the group consisting of a glycol, an ether, aglycol ether and mixtures thereof having the formula R¹—(OR²)_(x)—OR¹where x is an integer of 0, 1, 2, 3, or 4, R¹ is H or an alkyl groupcontaining from about 1 to about 10 carbon atoms, and R² is an alkylenegroup containing from about 1 to about 10 carbons atoms and combinationsthereof.
 10. The coating composition of claim 1, wherein the epoxyfunctional silane is represented by the formula R⁴ _(x)Si(OR⁵)_(4−x)where x is an integer of 1, 2 or 3, R⁴ is H, an alkyl group, afunctionalized alkyl group, an alkylene group, an aryl group, an alkylether, and combinations thereof containing from 1 to about 10 carbonatoms and having at least 1 epoxy functional group, and R⁵ is H, analkyl group containing from 1 to about 5 carbon atoms, an acetyl group,a —Si(OR⁶)_(3−y)R⁷ _(y) group where y is an integer of 0, 1, 2, or 3,and combinations thereof, R⁶ is H, an alkyl group containing from 1 toabout 5 carbon atoms an acetyl group, another —Si(OR⁶)_(3−y)R⁷ _(y)group and combinations thereof, and R⁶ is H, an alkyl group, afunctionalized alkyl group, an alkylene group, an aryl group, an alkylether and combinations thereof containing from 1 to about 10 carbonatoms.
 11. The coating composition of claim 1, wherein the carboxylicacid functional compound is represented by the formula R⁸(COOR⁹)_(x);where x is an integer of 1, 2, 3, or 4, and further R⁸ is H, an alkylgroup, a functionalized alkyl group, an alkylene group, an aryl group, afunctionalized aryl group, an alkyl ether, and combinations thereofcontaining from 1 to about 10 carbon atoms, and R⁹ is H, a formyl group,a carbonyl group, or an acyl group, where the acyl group can befunctionalized with an alkyl group, a functionalized alkyl group, analkylene group, an aryl group, a functionalized aryl group, an alkylether, and combinations thereof containing from 1 to about 10 carbonatoms, and where R¹ and R⁹ may or may not be joined by a chemical bond.12. The coating composition of claim 1, wherein the metal oxidecomposite colloidal component may contain any combination of alumina,silica, titania, zirconia, tin oxide, antimony oxide, iron oxide, leadoxide, and/or bismuth oxide, and further wherein at least one of themetal oxide components present in the composite mixture is neitheralumina nor silica.
 13. The composition of claim 1 wherein the colloidalsilica component is either acidic, basic, or neutral.
 14. The coatingcomposition of claim 13, wherein the colloidal silica component is anacidic colloidal silica component.
 15. The coating composition of claim1, wherein the tetrafunctional silane is represented by the formulaSi(OR¹⁰)₄ where R¹⁰ is H, an alkyl group containing from 1 to about 5carbon atoms and ethers thereof, an (OR¹⁰) carboxylate, a —Si(OR¹¹)₃group where R¹¹ is H, an alkyl group containing from 1 to about 5 carbonatoms and ethers thereof, an (OR¹¹) carboxylate, another —Si(OR¹¹)₃group and combinations thereof.
 16. The coating composition of claim 1,wherein the amount of water present in the aqueous-organic solventmixture is an amount sufficient to provide a substantially homogeneousmixture of hydrolysis products and partial condensates of all reactivecomponents.
 17. The coating composition of claim 16, further comprisingan effective amount of co-hydrolysis catalyst thereby enhancing thehydrolysis rates of the hydrolyzable components.
 18. The coatingcomposition of claim 1, further comprising an effective amount of acatalyst to thereby providing enhanced abrasion resistance to a curedcoating.
 19. The coating composition of claim 18, wherein the effectiveamount of the catalyst is from about 0.01 to about 2 weight percent,based on the total solids of the composition.
 20. The coatingcomposition of claim 1, wherein the aqueous-organic solvent mixturefurther comprises from about 0.1 to about 50 weight percent, based onthe total solids of the composition, of a mixture of hydrolysis productsand partial condensates of a silane additive represented by the formulaR¹² _(x)Si(OR¹³)_(4−x) where x is an integer of 1, 2 or 3, R¹² is H, analkyl group containing from 1 to about 10 carbon atoms, a functionalizedalkyl group, an alkylene group, an aryl group an alkyl ether group andcombinations thereof, R¹³ is H, an alkyl group containing from 1 toabout 10 carbon atoms, an acetyl group and combinations thereof.
 21. Thecoating composition of claim 20, wherein the amount of water present inthe aqueous-organic solvent mixture is an amount sufficient to provide asubstantially homogeneous mixture of hydrolysis products and partialcondensates of all reactive components.
 22. The coating composition ofclaim 21, further comprising an effective amount of cohydrolysiscatalyst thereby enhancing the hydrolysis rates of the hydrolyzablecomponents.
 23. The coating composition of claim 21, further comprisingan effective amount of a catalyst thereby providing enhanced abrasionresistance the cured coating.
 24. The coating composition of claim 23,wherein the effective amount of the catalyst is from about 0.01 to about2 weight percent, based on the total solids of the composition.